Signaling system and apparatus



,Mgrch 19, 1940. I 'R. F BL ANCHARD EIA 4 3,

SIGNALING SYSTEM AND APPARATUS 051mm; Filed Feb. 25, 1936 '7.Sheets-Sheet 1 REBLANCHARD W.B.BLANTON RNEY R. F. BILANCHARD ET AL ,8 1r SiGNALING SYSTBI AND APYARATUS Original Filed m, V25, 1936 7Shots-Sheet 3 Rf. BLANCHARD BY W.B. BLANTON \HL. BROWNE MGBW AT F Q m Ev0 RNEY Much 1940. v R. F. BLANCHARD ET AL 2,193,811

smmmne sYs'mu mm Arrmws Original fined Fob. 25, 1935- 7 Shots- Sheet 4 vD W W 1 Q 535350 mmBLM m 1 F 4 W maw m J 2d .1. F :7 o

R. F. BL'ANCHAIRDYETAL 2,193,811

- smmmme s sma AND APPARATUS Original Filed Feb 25, 1936 7 Sheets-Sheets l LTRS SHIFT s FIGS sun-"r e-- o(|234-9) v 7- |(234s--o) a- LTRS SHIFT9- w BLANK lO-BLANK INVENTORS v R.F. BLANCHARD W.B.BLANTON BY H.L.BROWNEs 5 f/d ATT RNEY 1 March 1940- R. F. BLANCHARD ET AL 2,193,811

SIGNALING SYSTEM AND APPARATUS Original Filed Feb. 25, 1935 '7Sheets-Sheet 6 'lllllll IL u 1940- R. F. BLANCHARD El AL ,193,

SIGNALING SYSTEM AND' APPARATUS I Original Filed Feb. 25, 1936 7Sheets-Sheet '7 I A RECEIVING B lNTERMEDlATE I C SENDING REPERF. 8 XTRumTs v SWITCHBOARD 200 I 55m 7 III III 204 201 ala INVENTORS RF.BLANCHARD W-B.BLANTON ATT RNEY Patented Mar. 19, 1940 SIGNALING SYSTEMAND APPARATUS Rolla F. Blanchard, Westfield, N. J., and William B.Blanton, Merrick,

and Harry L. Browne,

Brooklyn, N. Y., assignors to The Western Union Telegraph Company, NewYork, N. Y., a corporation of New York.

Application February 25. 1936,'Serial no. 65,702

I Renewed October 18,1939

33 Claims.

relaying messages through one or more oflices or stations.

In general terms the object of the invention is to expedite thetransmission of'signals, such as message groups of signals used intelegraphic communication, where a direct channel is not availablebetween the originating and final stations, as for example incommunication between a branch telegraph oflice connected to a centralofiice and'a remote oflice connected .to the central oflice through oneor more inter-city channels; and furtherto provide a method of andapparatus for automatically retransmitting groups of code signals, suchas permutation code signals received from a branch or subscriber'soflice, over a selected one of a plurality of circuits or channelsterminating in the main or central telegraph oflice under the control ofan operator or attendant in the latter oifice. The word channel is usedin a broad sense to include a metallic or phantom circuit, a channel ofa multiplex or carrier current system, etc.

In printing telegraph systems, it has been common practice in the caseof messages originating in branch or subscribers offices connected to amain or central ofiice in which inter-city trunks terminate to receivethe messages on printers at the central ofiice, transfer the printedmessage to a sending position having access to the outgoing trunk orchannel and retransmit the message manually. This method involves adelay or ofiice drag-in many instances but has the advantages that thetransmission is completely super-vised, the messages sent over eachoutgoing channelfihay be numbered consecutively to 'facilitate tracinglost or mutilatedmessages and the routing of messages may be altered atany time as required by trafiic conditions on the outgoing trunks fromthe central office or apparatus pose service signals, such asconsecutive numbers,

between groups of message signals so that supervision, routing andnumbering of messages follow present practice although manual handlingand retransmission are avoided. As will be apparent, the numbering ofmessages may be omitted if desired and certain features of the inventionare not limited in their application to printing telegraph systems ofthis particular character.

A further object of the invention is to provide a printing telegraphexchange system in which messages originating in branch offices' may berelayed through a switchboard or'other switching apparatus at thecentral office either to startstop printers of other local branchoffices or over multiplex channels terminating in said central ofiice.

A further object of the invention is to provide in a printing telegraphsystem having a main or central ofiice and one or more branch ofiices,receiving-storing devices such as reperforatortransmitters at thecentral ofiice and means under the control of an operator at the centralofiice for selecting an outgoing channel and rendering thereperforator-transmitter operative to relay messages from a branchoffice over the selected channel.

A still further object of the invention is to pro vide a printingtelegraph exchange system having a main or central oiiice, one or morebranch oiiices, selective switching means at the central oi'fice forautomatically relaying message groups of signals from the branch ofiicesto outgoing channels terminating at the central ofiice and double ormultiple storage means for storing the signals, such as storing devicesassociated with incoming channels and other storing devices associatedwith outgoing channels from the central office. Such a system simplifiesthe interconnection of start-stop printing apparatus with multiplexchannels and permits the operation of the several apparatus units atdifierent speeds, if desired.

A still further object of the invention is to provide a telegraphexchange system having improved means for interconnecting incoming andoutgoing lines or channels and for rendering the transmitting apparatusassociated with a pluralityof incoming lines operative in sequence whenthe lines are extended to the same outgoing channel.

Another object of the invention is to provide in a telegraph systemmeans for storing and repeating signals to control the operation o1? aremote printer or other receiving apparatus and ceipt of a predeterminedsignal by the printer or other receiving apparatus.

' Another object of the invention is to provide a telegraph exchangesystem having means for transmitting signals over a selected line orchannel, means for automatically stopping the transmission of signals incase the transmitting circuit becomes opened or grounded and/or meansfor operating a signal when the transmitting circuit is open orgrounded.

Other objects and advantages of the invention will become apparent fromthe following description of a preferred embodiment thereof shown on theaccompanying drawings wherein Fig. 1 is a'diagrammatic view of thegeneral arrangement of circuits and apparatus at a main or centraloiiice connected to three branch ofilces;

Fig. 2 is a front elevationalview of a portion of the switchbard withassociated receiving and transmitting apparatus at the main oflice;

Fig. 3 is a circuit diagram of the reperforatortransmitter andassociated circuits individual to each of the incoming lines from branchoflices;

Figs. 4, 5 and 6 are circuit diagrams ofthe apparatus associated withoutgoing lines or channels and with other units such as spilloverreperforators accessible through the switchboard at the main oflice; and

Fig. 7 is a diagram illustrating a modification wherein triple storageis employedl Referring to Fig. 1 of the drawings, a typical system shownby way of example comprises a plurality of branch or subscribers ofilcesBOI, B02 and B03 connected to the main or central oflice by lines Ill.II and i2, respectively. Other lines l3 and I4 extending to remoteofices terminate in a multiplex distributor MD and a terminal duplex setTDS, respectively.

In accordance with one feature ofthe invention, message groups ofsignals in printing telegraph code originating in a branch or remoteoffice are stored in the central oflice, and, under the control of anattendant at the central oilice,

are relayed or retransmitted over a selected one of the outgoingcircuits. Since certain of the transmitters or printers may be of thestartstop type and in other elements of the system synchronism may bemaintained by other means than the use of start-stop signals, theinvention provides for the interconnection of both types of apparatusand for the operation of the various units at different speeds in orderto obtain maximum efliciency.

In the embodiment of the invention shown, the start-stop transmittersTRI, TR2 and TR3 at the branch or subscribers oflices are connected tosignal storage devices, such as reperforators RRI, RR2 andRR3 at thecentral oilice adapted to record the messages on tape in a form adaptedto operate a tape transmitter. If desired, other types of storagedevices may be utilized such as metallic or electrical storage devicesarranged to store a suitable number of code signals to be subsequentlyrepeated. A storage device of the socalled infinite storage typeproviding a perm'anent record of both message signals and printedcharacters is preferred however. Each reperforator has associatedtherewith a tape transmitter 'I'I'l, 'I'IZ, TT3 for repeating the storedsignals, each transmitter being connected to switching means controlledat the central office for relaying the message over a selected line orchannel terminating at said oflice.

In its preferred form, the switching means at the central omce comprisesa switchboard of the conventional plug and jack type and constructed asshown in detail in Fig. 2. The plugs l5 are connected to cord circuitsindividual to the respective transmitters and the multipled jacks ii areconnected to circuits 20, 2|, 22, 23 and 24 to outgoing lines orchannels, or circuit 25 to reperforator RR4 for storing deferred orspillover messages, or circuit 28 to a printer RP4 at the localreceiving position. A transmitter TR4, for example, a keyboard tapeperforator and tape transmitter, is also provided at the local positionin the central oflice for sending messages originating at said office.The transmitter TR4 by means of its associated cord circuit andconnecting plug l5 may be connected to any of the circuits terminatingin the jacks I6. Messages recorded by the spillover reperforators RR4may be repeated by the associated tape transmitter TT4 through theswitchboard into any one of the outgoing lines. Similarly, messagesreceived over the lines l3 and I4 and recorded by the reperforators RR5and RR6 may be relayed through the cord circuits individual to theassociated tape transmitters 'I'I5 and TTS, respectively.

Each of the cord circuits is provided with control relays 30 adapted torender the associated transmitter operative under certain conditions, aswill be explained hereinafter in connection with the detaileddescription of the circuits shown in Figs. 3, 4, 5 and 6; to stop thetransmitter at the end of each message; and in connection with a circuitallotter CA to send messages in sequence in case more than onetransmitter is plugged into the same outgoing channel or switchboardcircuit at the same time. The circuit 20 from the switchboard to theline it includes a reperforator RR! having associated therewith a tapetransmitter 'ITI connected to one channel of themultiplex distributorMD. The circuit 20 further includes control relays 33 arranged inconnection with a numbering device 34 to interpose service signals suchas consecutive numbers between message groups of signals. The circuit 2|from the switchboard to the duplex signaling circuit l4 includes controlrelays 35 and a monitor printer MPR for recording the messagestransmitted in printed form. A numbering device 36 similar to the device34 may be provided if desired in connection with the signaling circuit14 or any of the other outgoing lines or channels. The circuits 22, 23and 24 from the switchboard to the branch oiiice lines I0, II and I2 areprovided with control relays 31 arranged to start the central oflicetransmitter upon the depression of a push button 38 by the branch ofiiceoperator who is signalled by the calling lamp or signal 39 when amessage is to be transmitted from the central oflice to the branchofllce. The circuits 25 and 26 from the switchboard to the spilloverreperforator RR4 and printer RP4 are provided with control relays 40 and4| operating in conjunction with the cord circuit relays 30 to close thesignaling circuits and start the connected transmitters at the beginningof a message and to open the signaling circuits at the I end of eachmessage.

Each group of message signals is followed by an end-oI-message signalwhich stops the tape transmitter in the cord circuit and releases theoutgoing channel or line so that another message waiting for saidchannel or line may be sent immediately. An operator or attendant at thecentral omce simply plugs each transmitter into the proper channel afternoting the destination of a message from the printed tape. The messageis sent automatically as soon as the selected channel becomes availableand no further attention is required of the operator except to withdrawthe plug upon receiving a signal that transmission has been completed.

In addition to the advantages accruing from the supervision and routingof messages in the central oflice, the system embodying the inventionpossesses material advantages over full automatic switching of telegraphcircuits wherein the selection of lines or channels is controlled fromthe originating office'., Special services may be provided, such astimed wire service, sending full rate messages ahead of. deferredmessages which are held in the spillover position, etc. The numbering ofconsecutive messages over heavily loaded channels greatly facilitatesthe tracing of lost or mutilated messages. Furthermore, since themessages are stored and repeated in the process of switching thecircuits, each stage of the transmission may be carried out at thehighest practicable speed and no difficulty is encountered in workingstart-stop transmitters into the synchronous distributors of multiplexsystems. This is advantageous because of the fact that many branchoifices are equipped with start-stop transmitters and the heavily loadedinter-city trunks are usually operated multiplex. It will be apparentthat various types of control or switching apparatus may be employed atthe central oifice for interconnecting lines and relaying groups ofsignals and that otherjmodifications in the system shown schematicallyin Fig. 1 and in detail in Figs. 3, 4, 5 and 6 may be made withoutdeparting from the scope of the invention. It is believed, however, thatthe specific types of apparatus units and their relationship asillustrated in the drawiings have certain advantages for use inmulti-ofiice printing telegraph systems of the usual character.

Fig. 2 illustrates a preferred arrangement of the switchboard andassociated storing and retransmitting apparatus. The portion of theswitchboard illustrated includes two vertical spaced panels 50 and 5|containing multipled jacks l6. Suitable labels 52 are arranged adjacentthe respective jacks in each panel and calling and supervisory lamps 53are mounted at the upper ends of the switchboard panels. printers,reperforatorsand tape transmitters associated with the cord and jackcircuits of the switchboard are mounted in tiers adjacent the respectivepanels, as shown. The panel 50 is associated with the inter-ofliceduplex trunk ll. The receiving reperforator RRG and tape transmitter TIBassociated with the receiving side of said trunk and the monitor printerMPR for supervising transmission into said trunk are mounted adjacentsaid panel 50. The cords connecting the respective transmitters to theplugs 15 are indicated by the dotted lines 54. The panel 5| isassociated with the multiplex inter-ofllce trunk l3 and the receivingreperforators RR5 and R and tape transmitters 1T5 and 'I'I5', and thesending reperforators RBI and RBI and tape transmitters 'ITI and TT'I'associated with two channels of said trunk are mounted adjacent saidpanel. The-switchboard panel associated with branch oflice lines II), IIand I2 may be similarly arranged except that, since no storage ormonitoring of the'code s'i'gnalstransmitted over said lines from thecentral ofllce is required, the three receiving units consisting ofrepertorators RRI, BB2 and RR3 and tape The.

'tion to the switchboard panels maybe varied depending upon thecharacter and number of ap-. paratus units required, the traflicconditions encountered and other considerations.

Detailed description The system shown diagrammatically in Fig. l isillustrated in detail in Figs. 3, 4, 5 and 6. Fig. 3 is a circuitdiagram of two cord circuits for extending calls from two tapetransmitters I'Il and TT2 to switchboard jacks IS in the same orseparate panels or sections of the switchboard. As shown in Fig. 1, eachincoming line whether from a local branch ofiice or remote omceterminates in a receiving-storing device and transmitter, such as a tapeprinter and reperforator,

and tape transmitter. In each case a cord cirsuit individual to eachtape transmitter is provided and thus the tape transmitter and cordcircuit shown in the upper half of Fig. 3 is illustrative of each of thereceiving and retransmitting units on incoming lines at the centraloflice. The transmitters and cord circuits at the spillover position andat the local sending position (Fig. l.) are also similar to those shownin Fig. 3.

The branch oflice, printers may be provided with start-stop simplextransmitters TRI, TR2 and 'I'R3 similar to the Tape Teletype (Model 14)described in Bulletin No. 126 of the Morkrum- Kleinschmidt Corporation.The receiving reperforators Rltl, BB2 etc., preferably print the messagecharacter as well as perforate a tape in such manner that when said tapeis passed through a tape transmitter, the message signals will berepeated, and may be of. the type shown in the patent to Rothermel, No.1,936,956, dated November 28, 1933, or that shown in the copendingapplication of Robert F. Dirkes and Evan R. Wheeler, Ser. No. 42,692,filed September 28, 1935. The tape transmitters associated with eachcord circuit may be of the type shown in the patent to Rothermel, No.1,805,374 dated May 12, 1931'.

The described system may utilize simplex, duplex or multiplextransmission channels of various types and the transmitting and storingwherein continuous synchronism is maintained between the two terminalstations or wherein start-stop impulses at the beginning and end of eachsignal are utilized to maintain synchrois not limited in respect to' thetype of circuits or apparatus employed or to uniform transmission ratesin difierent parts of the system as in the case of telegraph exchangesystems heretofore proposed. a

Transmission from branch office to second branch ofi'ice As shown inFig. 3, the line l0 extending to a branchv office where it is normallygrounded is connected through a switch 60 to the operating magnet 6| ofreperiorator RBI and to thewinding of a normally energized relay 62having the or recording apparatus may be either of the type otherterminal thereof connected tobattery. The first spacing signal receivedover the line 10 from the transmitter TRI causes the relay 62 to becomedeenergized, thereby closing the circuit of the calling lamp 63 throughthe right hand armature and back contact of said relay. The winding ofrelay 62 is short-circuited through its left. hand armature and backcontact and the signal lamp 53 remains lighted until the switch 84 isopened after completion of transmission of the message. The message isrecorded in the form of a perforated tape by the reperforator RBI andpreferably also printed upon the same or another tape as in theapparatus described in the patent to Rothermel, No. 1,936,956, and thecopending application of Dirkes and Wheeler referred to above. In thecase of messages received over a duplexed or multiplex line, themessages are recorded and a lamp or other signal operated in a similarmanner. The messages are thus cleared out of the originating ofllcewithout delay because of busy channels at the central office or othercauses.

The tape transmitter TI! is associated with the reperforator RRI and isconnected to the switchboard through a cord circuit 65 individual to theline In and terminating in the plug ii. The line H is provided withasimilar reperforator RR! andtape transmitter TH, and messages receivedover said line are relayed through a second cord circuit ii individualto said transmitter and line to an outgoing line or switchboard circuitaccessiible from the jacks I8. The cord circuits individual to therespective incoming lines are all identical and therefore the detaileddescription of the cord circuit individual to line l (Fig. 3) willsuflice.

Upon receiving a message upon the reperforator RRI, the operator notesthe destination of the message from the tape and plugs the cord circuit65 into the jack l6 corresponding to the proper outgoing line orchannel. Assuming that this is the line I! to branch oflice B03, (Fig.4)

type of receiving equipment. Each Jack I coma,

prises tip and sleeve contacts adapted to receive the tip and sleeve ofthe plug II. The tip circuit is employed to transmit the code signalsfrom the tape transmitter associated with the cord circuit to thereceiving apparatus and the closing of the sleeve circuit causes thetransmitter to seize the outgoing line or channel if it is idle andrenders typical circuits have been illustrated in Figs. 4, 5 and 6.

When the switchboard plug i5 is raised for insertion into a switchboardjack, the plug seats switch '12 is closed thereby closing a circuitthrough switch 13 and left hand inner armature and back contact of relayH for lighting the supervisory lamp II. The plug seat switch 12 closes asecond circuit through the winding of slow release relay l6 and theright hand inner armature and back contact of relay I! to energize relay16. The energization of relay 16 opens the circuit through the startmagnet SM of transmitter 'ITI to guard against premature starting of thetransmitter.

Assuming as stated above that the connection is to be extended to astart-stop printer at branch office B03 and the plug I5 is inserted intoJack Ii connected to conductors i and :i, a circuit is closed throughthe winding of relay 18 (Fig. 4), conductors II and i, sleeve of jackl6, sleeve of plug l5, right hand winding of test relay ll, resistanceII, and the right hand armature and back contact of relay H to the brush"of circuit allotter CA. The circuit allotter CA comprises a pluralityof spaced brushes, one for each cord circuit, and a rotating groundedsegment 82 arranged to connect each of said brushes momentarily andsuccessively to ground. If the line to branch ofilce B03 is idle, relaysII andbe come energized, when segment 82 engagesthe brush 8|. If theline has been seized by a second cord circuit, the multipled jacksindividual to said line will be busy" as described below and test relayII will not be operated until the connection has been released. I

If the selected line is idle, the energization of test relay 1! closes acircuit from positive battery through the winding of relay Ii,conductors II and 1', sleeve; of jack I! and plug ll, windings of relays83 and 84, left hand armature and front contact of relay 1!, left handwinding of relay 1!, right hand armature and back contact of slowrelease relay .5, left hand outer armature and back contact of relay 1'!and the armature and back-contact of relay I to negative battery,thereby energizing relays l3 and II. The energization of relays 83 and84 places a ground on the described circuit between the windings ofrelays N and I through a circuit including the armature and frontcontact of relay II and the left hand armature and front contact of slowrelease relay 84. Thus the relay II and 83 are locked up as long asrelay '4 is operated and the potential of sleeve of Jack I is such thatthe test relay of another cord circuit will not operate when connectedthereto as the resistance of the test relay circuit is large compared tothat of relay .3.

The energization of relay IO reverses the potential of the line I!extending to the branch ofilce B03 through a circuit leading from theinner armature of said relay through the winding of marginal relay l1,outer armature and back contact of relay II, line It, operating magnetII and the normally closed rest contact of the transmitting contacts llof the receiving printer RPS, winding of the polarized relay II andresistance I! to ground. The polarized relay II responds to the changeof polarity of the line and closes the circuits of the calling lamp 3!and buzzer I to notify the operator at the branch oiilce that the mainoffice desires to transmit a message. The marginalrelay "does notoperate on normal line current and therefore does not close its contactsuntil the line current isincreased as described below.

The attendant at branch office B03 may initiate transmission of themessage, after starting the printer motor or completing any otherpreliminary operations, by momentarily closing switch 38. The contactsof switch 38 are arranged to short-circuit the resistance 92 wherethrough its armature and back contact and the, outer armatures and frontcontacts of relays 94 and 18 for energizing .relay 88. The outer arma-'ture of relay 88 is connected to the line I2 and the energization ofsaid. relay transfers the line from the contacts of relay 'I8 to the tipconductor II which is connected through the tip contacts of theswitchboard plug and jack, the right hand armature and front contact ofrelay 84, the winding of relay 95; the winding of marginal relay 86, thenormally closed rest contact of thetransmitting contacts 96 oftransmitter 'I'II and resistance 91 to negative battery.- Thetransmitter TTI is now connected to the line wire in readiness to starttransmission.

Since the line I2 is now connected to negative battery at transmitter"I'Il, the armature of the polarized relay 9| is actuated to open itscontacts, thereby extinguishing signal lamp 39 and opening the circuitof-the buzzer 93 at the branch oflice B03. Relay 95 is energized butmarginal relay 86'is adjusted so that it will not operate on normallinecurrent. It will operate, however, if the line current is increasedby the closure of switch 38 or contact I08 in the printer RP3 inresponse to the transmission of the endof-message signal as describedbelow; it will also operate if the line between the main ofiice and thebranch office becomes grounded. Relay 86 is arranged to stop thetransmitter TTI, as will be described hereinafter, and thus thisoperation may be effected manually by the attendant at branch oflice B03or automatically in response to the transmission of the end-of-messagesignal orthe occurrence of a ground on the line circuit.

Upon the energization of relay 95, a circuit is closed from batterythrough the winding of slow release relay 85, the armature andfrontcontact of relay 95 and the winding of relay 98 to ground, whereuponrelays and 98 become energized. Relay 98 closes a locking circuit foritself and relay 85 that is independent of relay 95. Upon theenergization of relay 85,'a circuit is closed through its lefthandarmature and front contact for energizing relay' I4, and at itsright hand armature and back'contact relay 85 opens a.

short-circuit around the winding of relay 'II whereupon relays I4 and1'! become energized. The energization of relay "opens the circuit ofsignal lamp I5 at its left hand inner armature, extinguishing said lampto indicate to the attendant that transmission" of the message hasstarted, and closes through said armature a looking circuit for saidrelay through switches 12 and 13. right hand winding of test relay 19 tothe circuit allotter CA and closes a circuit from the latter to thewinding of relay 88 whereby the winding of under normal conditions.

The relay 14 also opens the circuit from the the said relay isperiodically short-circuited. The purpose of this arrangement is toguard against transmission into. an open line between the central ofliceand they branch or remote oflice as will be explained below. i

The energization of relay H, as above described, opens at its innerright hand armature and back contact the circuit of slow release relay16 whereupon this relay becomes de-energized and closes the circuit ofthe start magnet SM of the tape transmitter TTI. The delay in closingthe start circuit of transmitter TTI permits the printer RP3 to come torest if the cam shaft of the printer was released upon the reversal ofthe polarity of the line I2 by the operation of relay 88. The circuit ofthe start magnet SM includes the armature and back contact of relay I6and the left hand inner armature and front contact of relay I1. Upon theenergization of the start magnet SM, the transmitter TTI starts totransmit the signals stored in the tape from the reperforator RRI overthe line I2 to the printer RP3 at branch oflice B03.

If the line I2 should become opened or grounded after transmission hasstarted, it is desirable that transmission be stopped automatically toprevent loss of signals. To this end the operation of the transmitter'I'II is controlled in accordance with the condition of the line in asimple and effective manner and without interrupting transmission Relayis connected in series with the line so as to be traversed by thesignaling currents. Therefore, each time the signaling circuit isinterrupted, relay 95 becomes dc-energized. As pointed out above, relay98 is periodically de-energized by the circuit allotter CA whichperiodically closes a shortcircuit around the winding of relay 98through the right hand armature and front contact of relay The circuitallotter is preferably con-' structed to effect this result everytwo orthree seconds or at even shorter intervals. Since the ground connectionthrough the circuit allotter CA is of low resistance, relay 98 becomesde-energized every time the brush 8| contacts with the segment 82. Ifrelay 98 is de-energized at the same time that relay 95 is de-energized,the circuit of relay 85 will be opened. Relay 85 is a slow release relayand its armatures will not be released immediately. If the line I2 tothe branch offlce B03 is in operable condition and is not open, amarking signal willbe transmitted over said line with a minimumfrequency of once in each character transmitted, thereby reenergizingrelay 95 and reclosingthe circuit of relay 85,within a; definite timelimit. The slow release relay 85 is adjusted so that it will not releaseduring such time limit and therefore when the line is in operablecondition, relay" 95 will reclose the circuit of relay 85 through thearmature and winding of relay 98'beforerelay 85 opens its conengagementof segment 82 with the contact 8I of the circuit allotter CA, relay 9will become deenergized. The'deenergization of relay98 will open thecircuit of relay 85 and since the line circuit is open, relay 95 remainsdeenergized so that relay 98 cannot be reenergized and the circuit ofslow release relay 85 remains open. After a short interval of time relay85 becomes deenergized and closes at its right hand armature and backcontact a short-circuit around the left hand winding of relay 19. Thiscircuit may be traced from said winding to the right hand armature andback contact of relay 85, and through the left hand outer armature andfront contact of relay 1! to the other terminal of the left hand windingof relay l9. Thereupon relay 19 becomes deenergized and opens thecircuits of relays I1 and 84. When relay 1'! becomes deenergized, thecircuit of the start magnet SM of transmitter TTI is opened at the lefthand inner armature and front contact of said relay whereupon thetransmitter 'I'Il stops. The deenergization of relay ll also closes acircuit through its right hand inner armature and back contact,

the winding of slow release relay l8 and the contacts of plug seatswitch 72? to ground, whereupon relay it becomes energized and opens ata second point the circuit of the start magnet SM of transmitter I'Ti.

The deenergization of relay ll further closes a circuit through theright hand outer armature and back contact of said relay and the lefthand outer armature and front contact of relay i l for lighting signallamp 99, indicating that transmission has stopped. Relay l'l furthercloses a short-circuit around its own winding through its left handouter armature and back contact, and the right hand armature *and backcontact of relay 85. After the deenergization of relay l'l, slow releaserelay becomes deenergized, thereby opening at its right hand armatureand front contact the circuit'from the transmitting contacts 98 of thetransmitter TI! to the printer RP3 at the branch ofiice B03. Thedeenergization of relay 8 3 also opens the circuit of relays 33 and 78whereupon said relays become deenergized. All of the relays associatedwith the cord circuit 85 are now deenergized except relays i i and it.Relay T l may be deenergized by the attendant at the central ofiice byoperating switch 73 or both relays 7-! and it may be deenergized byremoving plug i5 from the jack and returning said plug to its seat,thereby opening the plug seat switch '12 and removing the groundconnection from the circuits of the windings of relays M and it. Theattendant at the central office will note that the message passingthrough the transmitter TTI has not been completely transmitted and willtake the necessary precautions to avoid the loss of said message.

When the line between the central oflice and the branch office isaccidentally grounded during the transmission of a message, transmitterT'I'l will be stopped in the following manner:The ground upon the linecircuit will cause the line current to be increased and thereby operatemarginal relay 8G. The operation of relay 8G. will open the batterysupply through its armature and back contact for the windings of relaysTi, 19 and 8d, whereupon relays I1 and 19 are deenergized and slowrelease relay 84 will be deenergized a moment later. The deenergizationof relay 1! opens at its left hand inner armature and front contact thecircuit of the start magnet SM of the transmitter TT! and thetransmitter stops. Relay ll also closes through its right hand innerarmature and back contact the circuit of relay l6 and this relay becomesenergized. At its right hand outer armature and back contact, relay l1closes the circuit of signal lamp 99 and this lamp is lighted toindicate to the attendant that transmission has ceased.

When relay 34 becomes deenergized, it opens areaen the circluit of thetransmitter IT! at the right hand armature and front contact of saidrelay. The deenergization of relay 84 further opens at its left handarmature and front contact the circuit of relays 83 and 18 whereuponsaid relays are deenergized. Relays and 86 are deenergized when thecircuit through the right hand armature and front contact of relay 84 isopened.

Upon the next engagement of brush 8| and segment 82 of the circuitallotter CA, the winding of relay 98 is short-circuited whereupon saidrelay becomes deenergized and opens the circuit of relay 85. Upon thedeenergization of relay 85 a short-circuit is completed around thewinding of relay '11 through the right hand armature and back contact ofrelay 85, and the left hand outer armature and back contact of reltay71. All of the relays in the cord circuit 65 are now deenergized exceptrelays M and 1B. Relay l l may be deenergized by the attendant at thecentral ofiice by opening switch 13 in the locking circuit of said relayor both relays it and it may be deenergized by returning the plug it: toits seat, thereby opening the plug seat switch 72 and removing theground connection from the windings of relays ill and it. The attendantat the central office will note that the message in the transmitter'I'Il has not been completely transmitted and will take the necessarysteps to insure against the loss of said message.

At the end of each message an end-of-message signal originally appendedto the message by the operator at branch office is transmitted by thetransmitter, as for example, a bell signal which operates upon a codesignal corresponding to the upper case J. When this end-of-messagesignal is received in the printer RPS (Fig. 4) the operation of theprinter in response to said signal will cause contacts Hill of theprinter to close momentarily thereby providing a shortcircuit path toground around the resistance 92. In this manner the line current in thecircuit is momentarily increased and marginal relay 86 becomesenergized. The energization of relay 86 opens the battery circuit ofrelays ll, 79 and 8:3, whereupon relays l1 and F9 are immediatelydeenergized and slow release relay 8t becomes deenergized a momentlater.

When relay 7? is deenergized, the circuit of the start magnet of saidtransmitter TTI is opened and the transmitter stops even though theremay be another message awaiting transmission in the tape. Thedeenergization of relay l7 closes a circuit through its right hand innerarmature and back contact for energizing relay l6 and upon the operationof relay 16, the circuit of start magnet SM of transmitter TT! is openedat a second point. The deenergization of relay 7! further closes throughits right hand outer armature and back contact the circuit of signallamp 99, whereupon this lamp is lighted to indicate that transmissionhas ceased.

Upon the deenergization of relay 8 3 the circuit of the transmittingcontacts 96 of the transmitter TTI' is opened at the right hand armatureand front contact of said relay. The deenergization of relay 84 furtheropens at its left hand armature and front contact the circuit of relays83 and I8 whereupon relays 83 and it become deenergized. The circuit ofrelays 86 and 95 is 85 and 98 in shunt to the contacts of relays 98 75whereupon these relays become deenergized as soon as the groundedsegment 82 of the circuit allotter CA effects the short-circuiting ofrelay 98. Upon the deenergizatlon of relay 85 the circuit of relay 14 isopened but this relay remains energized through its locking circuitincluding switches I2 and 13. Thus it will be seen that as a result ofthe -end-of-message signal, transmitter TTI has been stopped, the linefrom said transmitter to the branch omce has been opened at the contactsof the relay 94, the signal lamp 99 lighted, and all the cord circuitrelays except relays I4 and 16 have been deenergized. The circuitallotter CA will now function to cause any other cord circuit which maybe waitingfor a connection to the branch office B03 to be connected tosaid station through the line II in the manner already described. Thetransmitter 'I'II will not be reconnected to the line I2, however,

because relay I4 remains energized and thus holds open the circuit ofthe test relay 19 which initiates the operation of the controlapparatus. Therefore, although the plug l5 may be allowed to remain foran indefinite time in the jack I6, the connection so established willhave no effect and messages that may be awaiting transmission at otherpositions for branch office B03 will be sent.

The signal lamp 99 is lighted, however, to notify the central ofiiceattendant that transmission of the message has been completed and thetrans- ,mission circuit released. If there is ,another message awaitingtransmission on the tape from v the reperforator RRI, this message maybe destined either for the same branch ofiice B03 or for another branchor remote ofiice. If there is no other message on the tape from thereperforator RRI the. attendant in response to the lighting of lamp 99removes the plug.l5 from the jack and restores it to its seat. Thecontacts of the plug seat switch I2 are opened, thereby opening thecircuits of relays I4 and I6 whereupon th'ese relays become deenergizedand the lamp 99 is extinguished. The cord circuit and associatedapparatus are now restored to normal.

If there is another message on the tape destined for branch ofiice B03,it is unnecessary to withdraw the plug from the jack. The operatormerely actuates the 'switch.I3 to open momentarily the locking circuitof relay I4 whereupon this relay becomes deenergized and the lamp 99 isextinguished. The deenergization of relay ll closes through itsinnerleft hand armature and back contact the circuit of lamp I5, andthrough its right hand armature and back contact connects the test relayI9 to the circuit allotter CA. Relay I6 remains energized and prevents apremature closure of the circuit of the start magnet SM of thetransmitter TTI. The connection of the transmitter to the line to thebranch oflice B03 as soon as the line is idle takes place in the mannerdescribed above.

If there is a message on the tape destined for another outgoing channelor circuit allotted to a jack IS in the switchboard, theplug I5 iswithdrawn and restored to its seat, thereby opening the, contacts ofplug seat switch" I2 and deenergizing relays I4 and 16. The plug is theninserted in the jack connected to the desired channel or circuit andtransmission of the message follows in the .usual manner.

In the foregoing description it was assumed that the selected line, i.e-.'the line I2 to branch office B03, was idle when the transmitter T1!was connected theretoby the associated plug l5 and cord circuit 65. Ifthe line is busy because of a prior connection" to another transmitterand cord circuit, the transmitter TTI is held inoperative until thetransmission of the first message is completed and the line is released.If more than two transmitters are connected through their cord circuitsto the same line or circuit, the circuit allotter CA renders thetransmitters operative one after the other without attention from theoperator or attendant.

If the line I2 has already been seized by another transmitter before thetransmitter'TTI is plugged into the switchboard, the conductor a of theswitchboard multiple is connected to ground through the sleeve of theplug l5 of the other transmitter, the winding of the relay correspondjing to relay 83 and the contacts of relays corresponding to relays 83and of the cord circuit 65. The test relay I9 therefore does not operatewhen ground is applied to the right hand winding thereof by the circuitallotterCA and to transmit over said line'as described above upon thefirst engagement of segment 82 of the circult allotter with brush 8|.

Interojfice transmission with numbering of suncessive messages As shown,the system embodying the invention provides means for inter-posingservice code signals such as consecutive numbers betweensuccessivemessages in connection with transmission to remote oflices over duplexcircuits or multiplex channels. The service code or numbering mechanismmay also be employed in connection with the local branch omce lines, ifdesired, but ordinarily is not required because of the small volume oftraffic to such oilices.

The switchboard circuit leading to the terminal duplex set T138 and lineI 4 is shown in the lower half of Fig. 4, the service code signaltransmitter or. numbering mechanism 39 individual to 'saidline beingshown diagrammatically in Fig. 5.

messages, or other desired characters which may be different forconsecutive messages. In this manner themessage as receivedincludesarbitrary characters for the purpose of facilitating the tracing. oflost or mutilated messages or for other purposes. The code signaltransmitter shown in Fig. 5 is of the motor-driven cam switch typedescribed and claimed in the copending application of Dirkes, HooverandWheeler, Ser. No. 51,522, filed November 25,, 1935, but may be of anysuitable type, for .example, one in which the code signals are stored ina perforated tape or other storage medium.

In the embodiment of the invention illustrated,

when a messag'etransmitter is connected to the trunk I d or a channel ofthe multiplex circuit I3, the associated numbering mechanismautomatically transmits code signals of identifying character over thetrunk or channel and thereafter the connected transmitter. is renderedoperative to transmit the message stored in the associated reperforator.The trunk or channel is released by an end-of-message signal and thenext message over the same channel is preceded by a different codesignal group set up in the numbering mechanism so that each message asreceived includes distinctive identifying characters or numbers.Secondary storage of signals is preferably utilized in connection withtransmission over multiplex channels in order to simplify theswitchboard circuits and provide for varying rates of transmission indifferent parts of the system as required for maximum efficiency in theoperation of both exchange apparatus and transmission circuits.

Assuming that a message is to be relayed from branch oihce BOI to aremote ofi'ice connected to the duplex line I4, the message is initiallyprinted and stored at the central oflice by the combined printer andreperforator RRI (Figs. 1 and 3) as described above. After noting thedestination of the message on the tape, the attendant at the centraloffice plugs the cord circuit associated with the tape transmitter'I'I'I into the jack I 5 allotted to the outgoing line H, therebyextending the connection to the conductors k and Z of the switchboardmultiple and the conductors i ii) and III (Fig. 4). It is assumed thatthe monitor printer MPR and the receiving printer at the remote terminalof the duplex line I i are of the start-stop type and accordingly may beconnected directly to the transmitter TTI.

When the plug I5 is inserted in the jack 15, the plug seat switch 12 isclosed, thereby lighting the signal lamp 15 and energizing relay 16. Ifa connection is not already established with the line I d, the testrelay 19 becomes energized through a circuit including the brush 8! andthe grounded segment 82 of the circuit allotter CA, the right handarmature and back contact of relay 15, resistance 80, the right handwinding of relay 19, the sleeve contacts of plug I5 and jack I6, conductors I and Hi, switch .H2 and winding of relay H3 to battery,whereupon relays 19 and I I3 are energized. If the line It is busy, thesleeve of the jack IE will be at a potential indicating busy conditionas described above and the op- .eration of test relay 19 to initiate theoperation of transmitter TTI will be prevented until the line HI becomesidle.

Upon the energization of relay 19, relays 83 r and 84 become energizedthrough a circuit including the armature and back contact of relay 86,left hand outer armature and back contact of relay 17, right handarmature and back contact of relay 85, left hand winding and armature ofrelay' 19, windings of relays 84 and 83, sleeve contacts of plug I5 andjack I6, conductors I and Hi, and winding of relay H3. The switch H2 inseries relation with relay H3 is provided for the purpose of renderingthe channel It or the multiple jack circuit equipment associated withterminal duplex set 'I'DS busy if it is desired to prevent any cordcircuit from seizing said channel. If the switch H2 is open, theoperation of test relay 19 is prevented and the transmitter associatedwith a cord circuit plugged into the channel It will be maintainedinoperative. Relay H3, however, is provided with a. locking circuitthrough its left hand armature and front contact so that after thechannel has been seized and relay H3 energized, the circuit is notaffected by the opening of switch H2 until transmission of the messagehas been completed and relay H3 is deenergized.

The operation of relay 84 connects the tip circuit of the switchboardmultiple through its right hand armature and front contact and thewindings of relays and 86 to the transmitting contacts 96 of transmitterTTI. The transmitting circuit is interrupted, however, at the right handarmature and front contact of relay H4 as this relay remains deenergizeduntil the numbering mechanism 35 has completed its function. Theenergization of relay H3 closes a circult from ground through its righthand armature and front contact, the left hand armature and back contactof relay H4 and conductor lit for energizing the clutch magnet II1 ofthe numbering or service code signal transmitter 36 (Fig. 5), therebyinitiating the rotation of the transmitting cam drums of thetransmitter.

In the embodiment shown, the numbering mechanism 35 comprises aconstantly rotating drive shaft I25 connected through a clutch I26 tothe normally stationary cam drum I21. When the clutch magnet H1 isenergized, the clutch I25 is engaged and the drum I21 rotates with thedrive shaft I25. The clutch I25 is provided with a cam I28 and stop armlever I29 to disengage the clutch and stop the cam drum I2! in apredetermined start position after the clutch magnet M1 is deenergized.The numbering mechanism further comprises 2. letters code drum I30, aunits code drum IN and a tens code drum each of said drums beingintermittently stepped during the rotation of the transmitting cam drumI21. As shown, a Geneva cam I33 and Geneva wheel I34 are disposedbetween each pair of drums in such manner that the letters code drum I38is stepped'once for each revolution of drum I21, the units code drum I3Iis stepped once for each revolution of drum I31] and the tens code drumI32 is stepped once for each revolution of drum I3I.

Each of the rotatable drums is provided with projecting pins or cammembers I35 adapted to engage movable contact members I36 havingcooperating front and/or back contacts. The

operation of the contact members I36 in properly timed relation and inpredetermined sequence by the drums I21, I39, I3I and I32 is arranged tosend marking and spacing signals to a storage reperforator or the remoteprinter to print suitable characters which are appended to the messagefor the purpose mentioned above. The code signals sent automaticallyduring each cycle of operation of the numbering mechanism 36 may bereadily changed by properly rearranging the pins I35.

The mechanism 35 further comprises a relay I40 and a restoring switchIII, the latter being used for restoring the units code drum I3! to apredetermined starting position when desired. The tens cam drum I32 ispreferably also arranged to permit resetting manually when desired, asfor example, by disengaging the Geneva wheel I34 of said drum from thecooperating cam I33, thus permitting the drum to be turned to itsstarting position as described in the above mentioned copendingapplication of Dirkes, Hoover and Wheeler.

Upon the energization of the clutch magnet H1, the transmitting cam drumI21 rotates and during each rotation, a character or code si nal istransmitted over the conductor I45. Ten

revolutions of the cam drum I21 c'onstitute one interval, five markingor spacing impulses and a stop or current pulse whereby the signals areadapted to control the ordinary start-stop printer. When battery isconnected to the conductor I45, the operating magnet I46 of the monitorprinter MPR at the central office and relay I41 of the terminal duplexset TDS are energized, the circuit of said magnet and relay including aresistance I48 which is short-circuited by the closing of contacts I49of the monitor printer. The monitor printer MPR and relay I41 thusrespond to the signals transmitted by the numbering mechanism 35.

As shown, the movable contact members I36 of the transmitting cam drumI21 are connected together and to the conductor I45. Battery isconnected to theback contact I50 cooperating with the first or restcontact member I36 of drum I21. Upon the initial movement of drum I21from its normal position, the circuit including contact I50 is openedthus opening the line during the start interval. This circuit remainsopen until the drum I21 returns to its initial position. After fivesuccessive impulses are sent to the line by the successive operation ofthe remaining'contact members I36 of drum I21, the drum completes onerevolution and recloses the line circuit through contact I50 to send thestop pulse. The code signal sent during each revolution of drum I21 iscontrolled by con-.

necting or removing battery potential from the make contactscorresponding to the second, third, fourth, fifth and sixth contactmembers I36 of drum I21 in accordance with the setting of code drumsI30, I3I and I32. The ten revolutions of drum I21 during each cyclecause drum I30 to make one complete revolution and drum I3I to makeone-tenth of a revolutionduring each cycle of the numbering mechanismwhereas the tens code drum I32 is stepped once in ten cycles.

The first five contact members I36 of drum I30 are connected to the makecontacts of drum I21 and when actuated are connected to battery throughthe back contact I5I of the sixth con tact I36 of drum I30. In thenormal or first position of the code drum I30,.the code pins 135engaging the cooperating contact members I36 of drum I30 connected tothe make contacts of drum- I21 may be arranged in accordance with thecode signal representing the letters shift. Upon the first rotation ofthe cam drum I21, a letters shift signal will be sent to the linetoadjust the printer MPR and the printer at the remote oflice to printletter characters. During the transmission of the stop and start pulsesby contact I50, the letters code drum I30 is stepped to its secondposition wherein the code representing a character identifying thechannel I4,

for example is set up on the pins." This character may be the letter Fwhere the characters FWA are employed to designate the line I4 to aremote .ofilce. Upon the succeeding rotations of drum I21 the signalsrepresenting W, A

and the figures shift are sent to the line under the control of letterscode drum I30.

In the sixth position of the letters code drum- I30, only the sixth andseventh contact members I36 of drum I30 are actuated by pins I36. Thesixth contact member I36 connects battery to the make contacts of drumsI3I and I32 through make contact I52 of drum I30. The

.IM and M5 (Fig.4).

seventh contact member I36 of drum I30 closes through its make contactI53 the circuit of transfer relay I40. The contact members I36 oftransmitting cam drum I21 are thus connected through the back contactsof drum I30 and the armaof letters drum I30 opens the circuit includingmake contact I53 and winding of relay I40, whereupon relay I40 becomesdeenergized and transfers the sending circuit from drum I32 to drum I3I. In its initial position, units code drum I3I is arranged to send asignal representing the digit 1 and during the successive cycles of thenumbering mechanism, drum I3I changes the code signal set up from i to2, 3, etc. In this manner the numbering mechanism 36 interposesconsecutive numbers from 01 to 99 or (1) between consecutive messages.

' In the eighth position of the letters cod-e drum I30, the sixthcontact member I36 of said drum is restored to normal, thereby breakingthe battery connection to the contacts of drums I3-I and I32 andconnecting battery to the make contacts associated with the first fivecontact members I36 of drum I30. Thedrum I30 is then operative to sendthe letters shift signal to the line and, during the ninth and tenthrevolutions of transmitting drum I21; to send blank or other desiredsignals. When the drum I30 is being stepped from its ninth position toits tenth position, the eighth contact member I36 of drum I30 appliesground potential momentarily to conductor I65, thereby energizing relaysRelay H6 breaks the circuit of clutch magnet I I1 at the left handarmature and back contact of said relay. At this moment cam I26 hasadvanced so far that stop arm lever I26 does not immediately engage camI20 and the transmitting drum I21 continues to rotatefor almostanotherrevolution. Then the cam I20 engages the stop arm lever I26 whenthedrum I21 isin its rest position wherein contact I50 engages itsassociated contact. member I36, and drum I30 has been restored to itsinitial position. When the drum I30 comes to rest at its initialposition, the described circuit of relays II4 and H is interrupted butthe operation of relay H4 closed a locking circuit for said relaysthrough its left hand armature and front contact and the right handarmature and front contact of relay II3 whereby relays H4 and H5remainenergized until transmission of the message has been completed.

The terminal duplex set TDS is conventionally shown in Fig. 4' ascomprising a differential line relay I60 having opposed windingsconnected to the line I4 and an artificial line I6I respectively. Thearmature of the transmitting relay I41 is connected to the mid-point ofthe windings of relay I60 so that the relay will transmitpositive andnegative signaling impulses over the line I4 without affecting the linerelay I60. Relay I60 will, however, respond 'to impulses received overthe line I4 to control the receiving reperforator RR6.

' The energization of relay I as described above iii tudinally, slidableon nects through the same armature and front contact the monitor printerMFR and terminal duplex set TDS to the transmitting contacts 955 of thetape transmitter 'I'I'l. The transmitting circuit includes the windingsof marginal relay 86 and relay 85. Relay 95 becomes energized, effectsthe energization orrelays 85, 8% I1 and 14, and initiates thetransmission of the message stored by the reperforator RR! as describedabove in connection with the retransmission of messages to a localbranch omce.

The numbering mechanism 35 remains inoperative until the line H3 isseized by one of the cord circuits for the transmission of anothermessage. The second message will be numbered 02 because of the steppingof the units code drum H35 to its second position by the rotation of thedrum L39; After nine cycles of operation, the rotation of the units codedrum I3! steps the tens drum 132 so that the succeeding message will benumbered 10. In this manner the messages transmitted over the line l5will be consecutively numbered. Obviously, any desired service codesignals may be interposed between the messages and the signals may beproduced in various ways by using other types of automatic codesignaling devices.

It is deshable to be able to reset the tens and units code drums of thenumbering device from time to time in order to number the first message01 for example atthe beginning of each day. The units code drum ldl isreset by closing the switch Mi, thereby closing a circuit for energizingthe clutch magnet Ml through the sixth contact member 536 and backcontact i5 1 of drum as: if thisdlum is on any other position thannumber one. The drums 521, i353 and lti arerotated by the drive shaft.525 until the drum I35 reaches its reset for #1 position where thecircuit is interrupted at contact 555 through the operation of theassociated contact member 236 bya code pin i215. The tens code drum 82is preferably reset to normal position manually, the Geneva wheel 53d ofsaid drum being long-lthe shaft of the drum to effect disengagement ofthe wheel from the cam 3233.

After the numbering mechanism has completed its function, thetransmitter 'ITi is rendered operative as described above to send themessage over the line H to the remote oilice. The endof-message signalcauses the contacts "9 of the monitor printer MFR, to close momentarily,thereby short-circuiting the resistance 8 in the transmitting circuit tocause the operation of marginal relay 88. ithe cord circuit 65 is thenrestored to normal as described above. It will be noted that its. secondcord circuit had seized the line I I before relays H3 and H! aredeenersized, the transmitter in the second cord circuit 7 would berendered operative immediately without waiting for the numberingmechanism 38 to function. This is prevented by slow release relay USwhich closes a shunt circuit around relays l l3 and 85 to ground throughits armature and front contact. The resistance of this shunt circuit isso chosen that relays i i3 and 83 will remain operated once they areoperated but that the test relay 79 of a second cord circuit will not beenergized in Series with the winding of relay 3. The line ii is thusmaintained busy for a short interval after relays I13 and H4 becomedeenergized to prevent a premature seizure of the line by the secondcord circuit.

This delay in the connection of another cord When the monitor printerMFR is switched to the numbering mechanism 36, the circuit of the magnetM6 of the printer may be opened momentarily by the armature of relay H4as it moves from its front to its back contact. This interruption of thecircuit if of suiiicient duration will cause the printer to function asif 2. letters shift signal had been received. It is necessary that theprinter complete its cycle and come to rest before thenumberingmechanism starts transmission in order to avoid the printing of falsecharacters ahead of the characters transmitted by the num beringmechanism, and this is accomplished by the slow release relay i 35.

In the case of a message to be retransmitted over a multiplex channel,for example, of the line it, the cord circuit is connected through plugi5 and jack it to conductors m and n of the switchboard multiple,thereby extending the connection to the conductors Hi3 and ill leadingto the control apparatus associated with the multiplex distributor MD(Fig. 6). If the selected channel is busy, the test relay ii) is notenergized and the tape transmitter associated with the cord circuit ismaintained inoperative as described above. If the channel is idle, acircuit is closed from battery through the winding of relay H2, switchH3 corresponding to switch H2 (Fig. 4), conductors W and n, sleevecontacts of jack E6 and plug 15, right hand winding of test relay is,resistance 88 and right hand armature and back contact of relay M toground at the circuit allotter CA whereupon relays lid and W2 becomeenergized. The energization of relay H2 closes a locking circuit throughits left hand armature and front contact that is independent oftheswitch H3 and closes a circuit through its right hand armature and frontcontact and the right hand armature and back contact of relay. lid forenergizing the clutch magnet 1 of the numbering mechanism The numberingmechanism 35 is similar in construction to the numbering mechanism butis arranged to send characters identifying the associated channel ofline it). During the operaticn or the numbering mechanism 3 3, which issimilar to that described above in connection with mechanism 36, thetransmitting circuit of the tape transmitter 'ITl is held open at theleft hand armature of relay I1 After the numbering mechanism 35- hascompleted its cycle, the contacts iltl are momentarily closed, therebyenergizing relays I'll and I'M. Relay H 3 transfers the sending circuitfrom the numbering mechanism 3E to the transmitter 'ITE and slow releaserelay H1 is a guard relay corresponding to guard relay I 85 describedabove. Instead of transmitting the permutation code signals directlyover the line, a reperforator RR! is provided for perforating a tapewhich may be fed into the tape transmitter 'I'Il having transmittingcontacts Ill connected to the transmitting segments of the distributorMD and a tape stepping magnet I ll connected to the local segment of thedistributor. The transmitter TI! and its connections to the multiplexdistributor MD may be similar to those shown in the patent to BenjaminNo. 1,298,440 dated March 25, 1919. It will be noted that thereperforator RR! is connected in a short intraofiice circuit over whichsignals may be transmitted if desired at a much higher rate than overthe channels of the multiplex.

The reperforator RR] records the message preceded by the service codesignals from numbering mechanism 34 on a tape and, upon receiving theend-of-message signal, closes the contacts I82 in the transmittingcircuit to operate marginal relay 88 and release the connection. Byproviding double storage of signals, at the cord circuit 5 transmitterand at the distributor MD, the circuits are simplified and the severaltransmittersmay each be operated at its most efflcient speed. Ifdesired, however, other methods of interconnecting start-stoptransmitters .to the multiplex 10 channels may be employed.

Incoming messages over the trunk I8, as shown in Fig. 1, are recorded bythe reperforator RES and subsequently repeated through a. selectedswitchboard circuit, either to local or spillover re- 15 ceivingapparatus or to another office, by the tape transmitter TT5. Theincoming messages over the duplexed circuit I4 are likewise stored andrepeated by the reperforator RRB and tape transmitter ,TTS through theinstrumentality of the 20 associated cord circuit. While only onereperi'orator is shown for receiving messages over the trunk I8,ordinarily the apparatus shown would be duplicated for each operatingchannel of each multiplex distributor in the central office. Like- 25wise the receiving equipment shown in connection with the duplexedcircuit It would be .duplicated for each similar circuit terminating atthe central omce.

Special services As pointed out above, an auxiliary storing device suchas the reperforator RM (Figs. 1 and 6) is provided which is accessiblethrough the switchboard at the central office. This reperforator is 35preferably of the type which both reproduces the printed characters ofthe message and records the code signals in a form adapted to operatethe associated tape transmitter TM. The tape transmitter 'I'Iil may beconnected to the switchboard through a cord circuitsimilar to thoseshown in Fig. 8 so'that the stored messages may be subsequently repeatedover any of the circuits termimating in the switchboard.

The reperforator RRd may be employed as a spillover storage device toclear out messages re ceived by the reperiorators RRI, RR2, BB3, RR5 andRRG, when traiiiic conditions are such that these messages cannot berelayed promptly and also for [handling deferred messages and other 56special services. In order to transfer a message to the 'reperforatorRRl, the plug i5 is inserted into the jack it connected to theconductors a and b of the switchboard multiple. Upon the insertion ofthe plug in the jack, a circuit is closed through the winding of relayI85 (see Fig. 6). switch I88 corresponding to switch II2 of Fig. 4,conductor b of the switchboard multiple, sleeve contacts of plug I5 andjack I8, right hand winding of'testrelay I9, resistance 88 and righthand armature and back contact of relay It to ground at the circuitallotter CA. If the reperforator RR! is not busy, the test relay 19becomes energized as described above and initiates the operation of theassociated tape transmitter to send 65 the message signals over the tipcircuit of the connecting plug and conductor a of the switchboardmultiple.

, The energization of relay I85'closes, through its left hand armatureand front contact, a locking 7 circuit that is independent of the switchI88 and, through its right hand armature and front contact, thetransmitting circuit from the contacts of the tape transmitter to theoperating magnet I8I of the reperforator RRI. Relay I88 associated 75-with reperforator RRl .is normally energized through a circuit includingresistance I89, winding of relay I81 and the right hand armature andback contact of relay I85. Upon the energization of relay I85 asdescribed above, relay I88 becomes deenergized and closes through itsright hand armature-and back contact the circuit of signal lamp I98. Thelighting of signal lamp I90 calls the attention of the operator orattendant at the central oflice to the message stored in thereperforator BRA. Relay I88 closes through its left hand armature andback contact a short-circuit around its own winding so that the lamp I98remains lighted until, the switch I! is opened by theattendant. When theend-of-m'essage signal is received by the reperforator RRA, the contactsI92 are closed, thereby short-circuiting the resistance I88 andinitiating the restoration of the cord circuit as described above. RelayI85 becomes deenergized thereby interrupting the transmission circuit toreperforator RRA. When the attendant clears out the message stored bythe reperforator RRA, the switch I9I may be opened to permit relay I88to become energized thereby extinguishing the lamp I98.

The multiple jack equipment associated with the local receiving positionis identical with that described above at the spillover position exceptthat a printer RP4 is provided instead of the reperiorator REA. Incomingmessages for delivery from the central oflice are relayed through v theswitchboard to the receiving printer RPd in precisely the same manner asmessages are transferred to the reperforator RR4, and the messages areprinted and attached to a message blank or prepared for delivery in anydesired manner.

Multiple storage transmitters are provided at the branch ofices,

secondary storage is employed wherethe signals v v are repeated over amultiplex channel of a circuit having synchronous distributor apparatus.

In. the application of reperforator-switching systems to the practicalrequirements of telegraph service, it may sometimes be desirable foroperating or other reasons to utilize double storage in connection withtransmission into both multiplex channels and circuits having start-stopsynchronous terminal equipment. In that case the outgoing lines I0, II,I2 and I4 are also provided .55 at the sending sides withstorage-transmitters 'of the same character as described above inconnection with the multiplex channels of line I3 except that the tapetransmitters are of the type designed to operate start-stop printers andmay be similar to the transmitters TTI, TT2 and TT3.

The operation of this equipment would be similar to that described abovein connection with transmission over the line I3.

One advantage of this arrangement resides in the fact that thetransmission rates between connected transmitters and reperforatorslocated in .the central office are not subject to the speed limitationsgoverning the operation of apparatus connected by long lines andtherefore may be materially higher-than the rates of transmission onsome or all of the inter-oiiice circuits, as

pointed out above in connection with transmission over multiplexchannels (Fig. 6).

A further modification embodying the inven-.75

tion and involving triple storage of message signals is illustrateddiagrammatically in Fig. '7. In this system, intermediate storagereperforators are provided between the receiving reperforators and thereperforators associated with the outgoing lines. Such an arrangementwould be desirable, for example, in a large oflce where a switchingoperator or groupof operators could not be expected to route allmessages directly to the proper outgoing line or channel.

As shown, the oifice or exchange is divided into sections A, B and C.The receiving section A is divided into a multiplex group Zilil, a trunkand way simplex group 20!, a simplex city group 2612 and a city or localperforating and relay group 2513. At each group of the receiving sectiona switchboard section 204 is arranged for relaying messages. The group200 contains printer reperiorators and tape transmitters as describedabove in connection with the system shown in Figs. 1-6 for storingmessages received over multiplex channels terminating at the ofiice. Ingeneral, the storage, repeating and switching units may be of the samecharacter as those already described. The group 29! of the receivingsection A contains printer reperforators and tape transmitters connectedto incoming simplex trunks and way circuits and group 292-containssimilar apparatus for storing and repeating messages from local or cityoffices. The group 293 contains the local sending equipment such askeyboard perforators and tape transmitters.

The intermediate section B of the exchange is divided into three groups2535, 203 and 26 Group 265 contains storing and repeating units forrelaying messages over simplex trunks and ways 'or destined for manualrelay or local delivery. Group 286 contains similar equipment forhandling local or city trafic and group 20? contains storing andrepeating equipment for handling special messages, such as spillover ordeferred messages, misroutes, etc. The reperforators in each group oftheintermediate section B may be connected to calling lines fromswitchboard 204 by finder switches 208 in order to reduce the number ofstoring and repeating units required as in the case of concentratingsystems in general use for connecting an idle one of a group of printersor receiving units to a calling line. A switchboard section 208 isprovided for each of the groups in the intermediate section B forselection of the proper relay channel by the intermediate operator.

The sending section C of the exchange is divided into groups 2H3, 2H,ZIE and 253. The multiplex sending group 210 is accessible throughmultipled jacks of the switchboard sections 20d and containsreperforators and tape transmitters for storing and repeating messagesover outgoing multiplex channels. The groups 2 and 212 contain similarequipment for relaying messages over simplex trunks and way circuits andover simplex lines to local or city oiiices, respectively. The group 213contains printers for recording local messages for delivery or manualretransmission. Each of the groups in the sending section C may beprovided with finder switches 214 similar to the Switches 208, thefinderswitches in groups 2), 2H and 2|2 being each individual to a multiplexchannel, a simplex trunk and a simplex local circuit selected by the Aoperator, respectively.

In the system illustrated, the switching operator at section A isrequired to difierentiate between local or city messages and messages tobe aieaeir relayed over outgoing trunks or channels. In the case ofmessages to be relayed over multiplex channels, the operator is furtherrequired to select the proper channel, the multiplex sending group 2H0being accessible through the switchboard sections 203. In a largeexchange, an operator could not be expected to route all messages to theproper sending circuits and in the arrangement shown, the messages to beretransmitted over simplex trunks and way circuits and local simplexlines terminating at the exchange are routed to groups 295 and 206 atthe intermediate section B. Likewise cleierred or spillover messages arerouted to group 28'! at the intermediate section. If desired, themessages to be relayed over multiplex channels could also be routed tothe intermediate section B but in most offices a large proportion of theload is carried by the multiplex channels and therefore the apparatusrequired at the intermediate position is greatly reduced by routing suchmessages directly from the receiving section A to the sending section C.

' The switching operator at group 205 of the intermediate section Bisrequired to select the proper simplex trunks individually at group 2H ofthe sending section C and to select group 213 in the case of messages tobe manually retransmitted. The switching operator at group 206 of theintermediate section is required to select the proper local or citycircuit for local messages and the operator at group 297 handlesspillover messages, misroutes, etc., as indicated diagrammatically. Ifan A operator cannot determine the proper routing for a particularmessage or obtain access to the desired channel within a reasonabletime, such messages may also be routed to group 2M thus reducing thedelay in transmitting other messages received subsequently on the samereperforator.

It will be apparent that by providing an intermediate switching sectionB, the size of the switchboard at the receiving position A is reducedand the duties of the A operator in respect to routing of messages arebrought within reasonable limits thereby minimizing-the chances ofdelays and errors in relaying messaages. The system has the furtheradvantage that a temporary overloading of one of the simplex trunks orcity circuits does not result in a delay in clear ing out a messagedestined for the overloaded circuit from the transmitter at thereceiving position with a consequent delay in the transmission of othermessages stored by the associated reperforator. The occurrence of suchdelays in clearing traffic from the receiving reperforators is likely toresult in an accumulation of trafdc for other trunks and cause temporaryoverloading which is reflected back upon the transmitters at thereceiving position. Thus an abnormal increase in messages awaitingtransmission at the receiving position is likely to occur. Underordinary conditions this difiiculty is avoided by storing messagesdestined for overloaded circuits at the intermediate section of theexchange as described above.

As pointed out above, the invention is not limited to the specific typesof storing, repeating or switching apparatus herein described.

.. going channel.

2. In a telegraph system, a central station, a plurality of telegraphchannels terminating at said central station, a character storage deviceindividual to each incoming channel for storing character signalsreceivedthereover, a plurality of outgoing telegraph channels at saidcentral station, a character storage device associated with eachoutgoing channel, manual switching means for connecting anyof said firstmentioned storage devices to any of said second mentioned storagedevices for transmitting characters from said first mentioned'storagedevices to said'second mentioned storage devices, means controlled bypredetermined character signals so transmitted for interruptingtransmission of characters from said first mentioned storage devices andmeans for transmitting characters from each of said second mentionedstorage devices over its associated outgoing channel.

3. In a telegraph system, a central station, a plurality of telegraphchannels terminating at said central station, a character storage deviceindividual to each incoming channel for storing characters receivedthereover, a plurality of outgoing telegraph channels at said centralstation, a character storage device associated with predetermined onesof said-outgoing channels, switching means for successively connectingthe first mentioned storage devices to said second mentioned storagedevices or directly to an outgoing channel for transmitting charactersfrom said first mentioned storage devices to said secondmentionedstorage devices or to said outgoing channel, means controlled bypredetermined character signals so transmitted for interruptingtransmission of characters from said first mentioned storage devices andmeans for transmitting characters from each of said second mentionedstorage devices over its associated outgoing channel. v

4. In a telegraph exchange system, an office, incoming and outgoinglines terminating thereat, signal storage devices associated with theincoming lines, other signal storage devices associated with theoutgoing lines, means for repeating the signalsstored in one of thestorage devices associated with incoming lines and for storing saidsignals in one of said other signal storage devices and means forrepeating the signals stored in said one of said other signal storagedevices over an outgoing line.

5. In a telegraph exchange system, an omce, incoming and outgoing linesterminating thereat, a receiving reperforator operable over one of saidincoming lines, means including a second reperforator for transmittingsignals over an outgoing line at a predetermined rate and means foroperating said second reperforator at a difierent rate in. accordance;with the signals recorded by the first mentioned reperforator.

6. In a telegraph, exchange system, an oflice,

character storage devices sage signals recorded by the first mentionedreperforator.

'7. In a telegraph exchange system, an oflice, an incoming line and aplurality of outgoing lines terminating thereat and means includingselective switching devices for repeating message signals received oversaid. incoming line over any one of said outgoing lines, said meansfurther including a receiving reperforator operable at a predeterminedrate by signals transmitted over said incoming line and asecondreperforator associated with the selected outgoing line operableat a rate higher than said predetermined rate in accordance with signalsstored by said receiving reperforator.

8. In a telegraph exchange system, an offlce, incoming and outgoinglines terminating thereat, a group of signal storage devices associatedwith the incoming lines, a second group of signal storage devicesassociated with the outgoing lines, a third group of signal storagedevices, means for repeating and storing signals from the first group ofsignal storage devices to the second group, and means for repeating andstoring signals from the first group of signal storage devices to thethird group and for thereafter storing said signals in the second groupof signal storages devices.

9. In a telegraph system, a central station, a plurality of incomingtelegraph channels terminating at said centralstation, character storagedevices associated with said incoming channels for storing charactersreceived thereover, a plurality of outgoing channels at said centralstation, character storage from said first mentioned storage devices tosaid second mentioned storage devices, means for adding supplementalcharacter signals to each message group transmitted by said firststorage devices and means for transmitting characters from each of saidsecond mentioned storage devices over its associated outgoing channel.

10'. In a telegraph system, a central station,

a plurality of incoming telegraph channels ter-' devices associated withI predetermined of said outgoing channels, meansfor transmitting messagegroups of characters said first mentioned storage devices at the end ofeach message group and means for transmitting characters from each ofsaid second men tioned storage devices over its associated out-,

going channel. v

11. In a telegraph system, a central station, a plurality of incomingtelegraph channels terminating at said centralstation, a plurality offor storing character signals received thereover at one rate, a plu-

